UV Talk Letter Vol. 5

Importance of the Topic

Integrating spheres are critical in UV-VIS spectrophotometry to accurately measure scattering or refractive solid samples such as powders, suspensions, and lenses, and to evaluate solar properties of building materials and coatings. These devices uniformly diffuse incident light, ensuring complete integration of transmitted or reflected components, which is essential for reliable transmittance, reflectance, haze, and emissivity measurements.

Objectives and Study Overview

This report reviews principles and practical applications of integrating sphere measurements in UV-VIS and IR spectrophotometry. It covers transmittance, reflectance, solar transmittance and reflectance according to JIS standards, comparison of relative versus absolute reflectance, and introduces Shimadzu’s new AA-7000 atomic absorption spectrophotometer series.

Methodology and Instrumentation

• Integrating Sphere Principle: Light enters a barium sulfate–coated sphere, scattering uniformly, with apertures for sample placement and detector.
• Transmittance Measurement: Baseline correction with blank or white standard; measurement of total and diffuse-only transmitted light; haze measurement using light traps.
• Reflectance Measurement: Relative reflectance against a barium sulfate standard for diffuse (0° incidence) and total reflectance (8° incidence).
• Solar Measurement (JIS R3106): UV-VIS-NIR spectrophotometer for 300–2500 nm, weighted by solar or visible spectra to calculate τv, ρv, τe, and ρe.
• Instrumentation Used: UV-VIS and UV-VIS-NIR spectrophotometers with integrating spheres; IR spectrophotometer with specular reflectance accessory; Shimadzu Solar Transmittance Measurement Software; AA-7000 AAS with dual atomizer and safety features.

Main Results and Discussion

• Integrating Sphere versus Direct Detection: The sphere ensures all scattered and refracted light reaches the detector, eliminating errors with scattering samples.
• Transmittance Variants: Open aperture mode isolates diffuse component; light trap mode improves turbidity accuracy.
• Reflectance Modes: Diffuse reflectance excludes specular component; total reflectance captures both by tilting incidence.
• Solar Properties: Four glass samples showed significant UV-VIS-NIR differences but similar IR reflectance, highlighting material selection impact on energy performance.
• Relative versus Absolute Reflectance: Relative measurements depend on the quality of the standard; absolute accessory yields instrument-independent reflectance within measurement error.

Benefits and Practical Applications

• Quality Control: Reliable transmittance and reflectance data for coatings, films, glasses, and suspensions in research and industrial QA/QC.
• Energy Efficiency Assessment: Solar transmittance and reflectance for building glazing, roof films, and paints conforming to JIS standards.
• Versatile Analysis: Integrating spheres support UV-VIS, NIR, and IR measurements, enabling haze, turbidity, and emissivity studies.

Future Trends and Opportunities

• Standard Expansion: Implementation of JIS A5759 for glazing films and JIS K5602 for paint films will require dedicated software tools.
• Enhanced Instrumentation: Larger spheres and advanced coatings will reduce sample scattering effects while minimizing noise.
• Automation and Software Integration: Streamlined data processing and calculation through specialized applications.

Conclusion

Integrating spheres are indispensable for accurate photometric analysis of scattering and refractive samples and for assessing solar thermal properties of materials according to international standards. Advances in absolute reflectance accessories and specialized software enhance measurement reliability and efficiency across research and industrial applications. Shimadzu’s AA-7000 series further extends analytical capabilities with high sensitivity, rapid mode switching, and advanced safety features.

Reference

• Shimadzu Application News No. A396 Daylight Transmittance Application Data of Glass Plate
• Shimadzu Application News No. A404 Glass Plate Analysis in Accordance with JIS R3106
• Shimadzu Application News No. A412 Analysis of Adhesive Films for Glazings Conducted in Accordance with JIS A5759